When a mobile phone is purchased, the customer may set up an account on which they are billed periodically for service and usage, or they may set up a prepaid mobile phone account on which they can purchase credit to use on a mobile phone network. For a pre-paid mobile phone, the user pays for cell phone use ahead of time and can then use the mobile phone network until the credit runs out. The pre-paid credit may be in the form of a number of minutes and/or a number of text messages. In some cases, credit on a pre-paid mobile phone may have a time limit, for example, 90 days from the time credit was purchased. When the credit runs out, the mobile phone user can add more credit to the account by various means (e.g., by entering a credit/debit card transaction on the phone, by accessing a third party software, by purchasing a top-up card at a retail store).